A relationship between frequency changes and mass loads caused by adsorption of a Quartz Crystal Microbalance (QCM) is expressed by Sauerbrey equation indicated by the following equation 14.
                              Δ          ⁢                                          ⁢          Fs                =                              -                                          2                ⁢                                  Nf                  0                  2                                                                                                  ρ                    Q                                    ⁢                                      μ                    Q                                                                                ⁢                                    Δ              ⁢                                                          ⁢              m                        A                                              Equation        ⁢                                  ⁢        14            
However, in the case of measurement in the field of chemistry, biochemistry, pharmacy, or the like in which the measurement is mainly made in a solution, since the solution is contained in an adsorption substance unlike in the atmosphere, the adsorption substance is known to be a film with viscoelastic properties. A frequency change of a resonance frequency Fs measured in conventional QCM has therefore indicated a value that includes a mass load due to adsorption, a viscous load of the solution, and a viscoelastic effect of the adsorption substance itself, and these three elements could not be separated.
Accordingly, the present applicant found from the invention described in Patent Document 1 that the three elements included in a frequency variation of the above Fs can be separated and respectively calculated as frequency variations.
However, even if conversion into mass can be made using the above Sauerbrey equation from a frequency change calculated by a separated mass load, a viscoelastic modulus of an adsorption substance cannot be calculated from a separated viscoelastic element.
Specifically, it was found from the invention described in Patent Document 1 that the three elements included in a frequency variation of the above Fs can be separated and respectively calculated as frequency variations. However, the mutual separation of amass load term, a viscous load term, and a viscoelastic term cannot be made in all of measurements, and there was a case that a calculated viscous change term was not zero even if there was no viscous change. Furthermore, each separated term was a value of a frequency, and a viscoelastic modulus could not be calculated.